Alloy comprising polyolefin and thermoplastic polyurethane

ABSTRACT

This invention relates to an alloy comprising polyurethane and polyolefin. It has now surprisingly been found that a specific composition of polyolefin and polyurethane has surprising mechanical properties and at the same time has transparent characteristics and/or appearance. The present invention provides an alloy with remarkable mechanical properties. The phases do not macro-phase separate. Thus, this stable and potentially broad interface is very effective in stress transfer when the alloy is strained. As one might expect, the hardness values for the alloys are in between the hardness values of each component but the other physical properties are no so adjusted. In this way, when considering the hardness and mechanical values, these alloys behave like two compatible polymers.

FIELD OF THE INVENTION

This invention relates to an alloy comprising polyurethane andpolyolefin.

BACKGROUND OF THE INVENTION

Thermoplastic polyurethanes (TPU) are fundamentally the reactionproducts of polyisocyanates and hydroxyl terminated intermediate, forexample, diols, and in some embodiments, long-chain diols. They comprisea broad family of compositions having both urethane segments andnon-urethane segments. Thermoplastic polyurethanes generally have no, oronly very slight, crosslinking and accordingly have a linear structure.Thermoplastic polyurethanes are well known to the person skilled in theart and are described by way of example in Kunststoff-Handbuch [Plasticshandbook], Volume 7, Polyurethane, ed. G. Oertel, 2nd edn., Carl HanserVerlag, Munich, 1983, particularly on pages 428, 473. Some thermoplasticpolyurethanes, and their preparation, are disclosed in U.S. Pat. No.4,542,170 and U.S. Pat. No. 4,397,974. U.S. Pat. No. 4,397,974 disclosespreparation of thermoplastic polyurethane elastomers by reacting along-chain polyol having molecular weight in the range of about 400 to10,000, preferably 800 to 6,000; with a polyisocyanate, preferably adiisocyanate; and a chain extender having a molecular weight of up toabout 400. The preferred chain extenders are short-chain polyols havingmolecular weight of up to 380. The equivalent ratio of isocyanate groupsto the active hydrogen atoms, or the NCO/OH ratio, is in the range of0.90 to 1.10, preferably in the range of 0.98 to 1.04.

Thermoplastic polyurethanes are often used in blends with othermaterials, including polyolefins. However it is often difficult toachieve a blend of thermoplastic polyurethanes and other materials,including polyolefins, that retain all of the physical propertiesdesired for the blend.

U.S. Pat. No. 4,883,837 describes a thermoplastic compatible blendedcomposition comprising a. from 15 to 60 weight percent of a polyolefin,b. from about 30 to 70 weight percent of a thermoplastic polyurethaneand c. from about 10 to 35 weight percent of a least one modifiedpolyolefin defined as a random, block or graft olefin copolymer havingfunctional groups selected from the class consisting of carboxylic acid,carboxylate ester, carboxylic acid anhydride, carboxylate salts, amide,epoxy, hydroxyl and acyloxy. The blends are described as soft, flexiblecompositions having high tensile and tear strength with goodprocessability and good adhesion to a wide variety of plastics.Applications include fabric coatings for upholstery, rainwear andsportswear and for production of surgical gloves, plastic laminating andthe like.

EP 0353673 A1 describes blends of a thermoplastic polyurethane elastomerand a carbonyl modified polyolefin with improved properties such asimpact resistance, low temperature toughness, low melt processingtemperatures, generally increased flex modulus and improves flexstrength. The amount of carbonyl modified polyolefin is generally about1 part to about 30 parts by weight for every 100 parts by weight of thethermoplastic polyurethane elastomer. The blends can be used to produceheat molded products for automotive applications.

EP 2279767 A2 describes a medical device, in particular a urinarycatheter, comprising a substrate, having on its surface a hydrophilicsurface layer providing a low friction surface when wetted by a wettingfluid. The substrate is made of a polymer blend comprising a polyolefinand a composition having molecules with active hydrogens, such aspolyamide or polyurethane. The preferred blend comprises at least 80weight percent polyolefin and therein possibly intermixed medical oiland/or paraffin, and 2-20 weight percent of the component havingmolecules with active hydrogens. This composition is described asenvironmentally acceptable and cost effective, has adequate mechanicaland chemical properties, and enables the hydrophilic coating to beadequately adhered.

UK Patent Application No. GB 2048903 describes a thermoplastic resinouscomposition consisting essentially of 5 to 70 weight percent of athermoplastic polyurethane elastomer and 30 to 95 weight percent of amodified polyolefin or an olefin copolymer, having functional groups ofat least one type selected from carboxyl, carboxylate salt, carboxylicanhydride, amide, hydroxyl and epoxy groups. An application of thethermoplastic resinous composition is a laminate having at least twolayers bonded to each other, at least one of the layers being comprisedof the above-mentioned resinous composition.

SUMMARY OF THE INVENTION

It has now surprisingly been found that a specific composition ofpolyolefin and polyurethane has surprising mechanical properties and atthe same time has transparent characteristics and/or appearance.

Our data show, that compounding TPU A or TPU E with a range ofPolyolefins (PO) results in an alloy with remarkable mechanicalproperties. The phases do not macro-phase separate. Thus, this stableand potentially broad interface is very effective in stress transferwhen the alloy is strained. As one might expect, the hardness values forthe alloys are in between the hardness values of each component but theother physical properties are no so adjusted. In this way, whenconsidering the hardness and mechanical values, these alloys behave liketwo compatible polymers.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Thus, one aspect of the invention relates to an alloy of a thermoplasticpolyurethane (TPU) and a Polyolefin (PO) having at least one of thefollowing properties:

the ratio between the surface tension of the TPU and the surface tensionof the PO measured above the melt temperature of the alloy is between0.5 to 1.5;

the PO contains at least one functional group that can form long rangeinteractions with one or more segments of the TPU;

the viscosity of the discrete phase over the viscosity of the matrixphase is below 2 under processing conditions.

The compositions of the invention include a thermoplastic polyurethane(TPU) component and a polyolefin (PO). The composition may be describedas an alloy of a TPU and PO, or as a blend of a TPU and PO.

The compositions of the invention include a thermoplastic polyurethane(TPU) component. Such TPU are made by reacting a polyisocyanate with atleast one diol chain extender, and optionally one or more hydroxylterminated intermediates.

In one aspect, the hydroxyl terminated intermediates include a polyesterpolyol, which are made by the polycondensation of multifunctionalcarboxylic acids and hydroxyl compounds. These are also referred to aspoly-ester TPU.

In another aspect, the hydroxyl terminated intermediates include apolyether polyol, which are made by the reaction of epoxides (oxiranes)with an active hydrogen containing starter compounds. These are alsoreferred to as polyether TPU. In general, polyether TPU has a lowersurface tension than polyester TPU. As PO typically has surface tensionscomparable to polyether TPU finding a matching PO to a polyether TPU iseasier.

Polyolefins are well known and commercially available materials.Polyolefins may be described as polymers of monoolefins and diolefins,for example polypropylene, polyisobutylene, polybut-1-ene,poly-4-methylpent-1-ene, polyisoprene or polybutadiene, as well aspolymers of cycloolefins, for instance of cyclopentene or norbornene,polyethylene (which optionally can be crosslinked), for example highdensity polyethylene (HDPE), high density and high molecular weightpolyethylene (HDPE-HMW), high density and ultrahigh molecular weightpolyethylene (HDPE-UHMW), medium density polyethylene (MDPE), lowdensity polyethylene (LDPE), linear low density polyethylene (LLDPE),(VLDPE) and (ULDPE).

Polyolefins can be prepared by various well known methods, including butnot limited to: radical polymerization (normally under high pressure andtemperature); and (b) catalytic polymerization using a catalyst thatnormally contains one or more than one metal of groups IVb, Vb, VIb orVIII of the Periodic Table.

Polyolefins, as used herein, also includes mixtures of one or more ofthe polyolefins described above. For example, in some embodiments thepolyolefins used in the invention are mixtures of polypropylene withpolyisobutylene, polypropylene with polyethylene (for example PP/HDPE,PP/LDPE) and mixtures of different types of polyethylene (for exampleLDPE/HDPE).

Polyolefins, as used herein, also includes copolymers of monoolefins anddiolefins with each other or with other vinyl monomers, preferablyaliphatic vinyl monomers, for example ethylene/propylene copolymers,linear low density polyethylene (LLDPE) and mixtures thereof with lowdensity polyethylene (LDPE), propylene/but-1-ene copolymers,propylene/isobutylene copolymers, ethylene/but-1-ene copolymers,ethylene/hexene copolymers, ethylene/methylpentene copolymers,ethylene/heptene copolymers, ethylene/octene copolymers,propylene/butadiene copolymers, isobutylene/isoprene copolymers,ethylene/alkyl acrylate copolymers, ethylene/alkyl methacrylatecopolymers, ethylene/vinyl acetate copolymers and their copolymers withcarbon monoxide or ethylene/acrylic acid copolymers and their salts(ionomers) as well as terpolymers of ethylene with propylene and a dienesuch as hexadiene, dicyclopentadiene or ethylidene-norbornene; andmixtures of such copolymers with one another and with any of thepolyolefins described above, for examplepolypropylene/ethylene-propylene copolymers, LDPE/ethylene-vinyl acetatecopolymers (EVA), LDPE/ethylene-acrylic acid copolymers (EM), LLDPE/EVA,LLDPE/EAA and alternating or random polyalkylene/carbon monoxidecopolymers and mixtures thereof with other polymers, for examplepolyamides.

Additional polyolefins also suitable for use in the present inventioninclude “linear low density polyethylenes” (LLDPE) which are preparedusing a coordination catalyst, but which, because of the presence ofminor amounts of copolymerized higher olefins (especially olefins of 410 carbon atoms) have a density lower than HDPE, yet the arrangement ofpolymerized molecular units is of the linear type.

It is also contemplated to use polyolefins, such as ethylene polymers,which contain other comonomers, such as acrylic acid, methacrylic acid,alkyl acrylates, vinyl esters, and carbon monoxide. These type ofmonomers, which contain oxygen atoms, are employed using a free-radicalinitiator, but are not very well suitable when coordination catalystsare employed. The coordination catalysts, which generally containmetal-carbon bonds, are usually poisoned or deactivated by compoundscontaining oxygen-carbon bonds or hydrogen-oxygen bonds when employed inquantities such as are involved in copolymerization thereof. On theother hand, copolymerization of ethylene with the higher hydrocarbonolefins is best done using a coordination type catalyst. In someembodiments the PO may include units derived from an oxygen-containingcomonomer, for example acrylic acid, such that the PO is at least 4, 6,9, or even 11 percent by weight comonomer. In some embodiments the POhas a comonomer content of 4 to 11 percent by weight, or even 6 to 11 or9 to 11 percent by weight. In some embodiments the oxygen-containingcomonomer is acrylic acid.

In one embodiment, the PO is selected from the group of polyethylene(PE), polypropylene (PP), copolymer of polyethylene, and copolymer ofpolypropylene, including a PE and/or PP containing comonomers such asacrylic acid, methacrylic acid, alkyl acrylates, vinyl esters, and/orcarbon monoxide.

In some embodiments the compositions of the invention have reducedinterfacial tension, in other words the difference between the surfacetension of TPU and the surface tension of the PO at the processtemperature is small. While not wishing to be bound by theory, it isbelieved that a sufficiently low interfacial tension is an importantvariable for ensuring the compositions of the invention to have thedesirable properties described herein, most likely because the lowinterfacial tension is required to allow a stable interface to formbetween the TPU and PO components of the blend. Surface tension may bemeasured by various means, including but not limited to the drop volumemethod, the Du Noüy Ring method, the Du Noüy-Padday method, the Wilhelmyplate method, the spinning drop method, the pendant drop method, thebubble pressure method, the capillary rise method, the stalagmometricmethod, and the sessile drop method.

A convenient way to describe the interfacial tension of the compositionsof the invention is to refer to the ratio of the surface tension of theTPU and the surface tension of the PO at the process temperature. Thecloser the ratio is to 1, the lower the interfacial tension of thecomposition. In some embodiments the ratio of the surface tension of theTPU and the surface tension of the PO is from 0.5 to 1.5, or even from0.8 to 1.2, or even from 0.9 to 1.1, or even about 1.0.

When referring to the process temperature in the above discussion ofsurface tension, we refer to the compounding conditions describedherein. In one embodiment that could be at 2° C. above the melttemperature of the alloy.

In one embodiment the surface tension ratio is determined by the stepsof:

-   -   run a DSC of the alloy to determine the melt temperature of the        alloy;    -   selectively separate the components of the alloy, for example by        solvent extraction;    -   determine the surface tension of each component by the modified        Wilhelmy balance technique    -   obtain the ratio by dividing the surface tension of the TPU with        the surface tension of the PO.

To form an alloy of the invention, starting with a particular PO, thesurface tension of a TPU needs to be adjusted to get a ratio as justdescribed. One such adjustment method is to vary the ratio between hardsegment (HS) and soft segments (SS) of the TPU. The HS are generallypolar, high melting segments formed from the isocyanate and chainextenders. The SS are generally less polar, low melting segments formedfrom high molecular weight polyols. The ratio between these two can bedetermined by NMR.

To decrease the surface tension of the TPU, it has proven advantageousto increase the SS content of the TPU. Likewise, the higher the HScontent, the higher the surface tension.

If the ratio between the HS and SS is held constant, the surface tensioncan be altered by adjusting the composition of the SS. That is, byincreasing the Mn of the poly THF used to form the SS, the surfacetension of the resulting TPU may be decreased.

In general, the surface tension of the TPU is higher than the surfacetension of the PO to be compounded with the TPU. Thus, typically thesurface tension of the TPU should be lowered. The Mn of the polyetherpoyol used in the preparation of TPU A is 2000 g/mol, and the Mn of thepolyether polyol used in the preparation of TPU E is 1,400 g/mol. Incontrast thereto, the Mn of the polyether polyol used in the preparationof TPU B and TPU D is 1,000 g/mol. It is therefore preferred, that theMn of the polyether polyol is higher than 1,000 g/mol, or in someembodiments at least 1,400 g/mol.

To form an alloy of the invention, starting with a particular TPU, thesurface tension of a PO needs to be adjusted to get a ratio as justdescribed. One method of increasing the surface tension of the PO is toco-polymerize and/or graft acrylic acid on the PO.

In some embodiments the PO present in the compositions of the inventionhave at least one functional group that allows for long rangeinteractions with one or more segments of the TPU present in thecompositions of the invention. While not wishing to be bound by theory,it is believed that a certain amount of long range interaction is animportant variable for ensuring the compositions of the invention havethe desirable properties described herein, most likely because the longrange interactions are required to allow the interface between the TPUand PO components of the blend, once formed, to stabilize. Long rangeinteractions that may be useful in the invention include ionic bonding,hydrogen bonding, and van der Waals interactions. In some embodimentsthe long range interactions are not covalent bonds. In some embodimentsthe long range interactions include hydrogen bonding.

Functional groups that can give rise to long range interactions withsegments of the TPU component, for example hydrogen bonding to one ormore segments of the TPU component, include functional groups with ahydrogen atom covalently bonded to an electronegative, such as an oxygenor nitrogen, atom. Carboxylate groups and maleic acid derived groups areexamples of functional groups that can make hydrogen bond to one or moresegments of the TPU component. Care must be taken, when using POcomponents having such functional groups, or when adding such functionalgroups to a PO, to minimize any increase in interfacial tension of theoverall composition. Ideally the functional groups being used and/oradded to the PO would be carefully selected to not only allow forhydrogen bonding to one or more segments of the TPU component, but alsoto minimize any increase in interfacial tension of the overallcomposition, and further to even reduce the interfacial tension of theoverall composition. In some embodiments, using acrylate (acrylic acid)groups in the PO accomplishes this goal.

In some embodiments the viscosity of the TPU and the PO are similar. Itis presently believed that similar viscosities helps to form a goodinterface between the TPU and PO components of the blend.

A convenient way to describe the similarity of the viscosities of thecomponents is to refer to the ratio (L) of the discrete phase of thecomposition over the matrix phase of the composition:

$\lambda = \frac{\eta_{d}}{\eta_{c}}$

where η_(c) is the viscosity of the continues phase and η_(d) is theviscosity of the disperse phase.

The closer the ratio is to 1, the more similar the viscosities are. Aschanges in viscosity are logarithmic it is preferred that the viscosityratio is between 10 and 0.1 such as between 3 and 0.3.

It is preferred, that the discrete phase is the PO phase, and the matrixphase is the TPU phase. Thus, an embodiment relates to an alloy whereinthe viscosity of the PO over the viscosity of the TPU is between 10 and0.1 under processing conditions.

As illustrated for example in Example 3, processing conditions can be arange of temperatures and pressures. This range is allowed, inter aliaif the compositions of the alloy have similar viscosity profiles (asillustrated in Example 8), and more specifically, similar viscosityprofiles under various shear rates and temperatures. In other words theviscosities of the TPU component and the PO component are similar acrossthe ranges of processing conditions the composition will experienceduring blending, especially shear rates. This offers a large window ofprocessing conditions suitable for forming the alloy.

The Weber number (We) is often used to characterize the dispersion ofdroplets:

${We} = \frac{\overset{.}{\gamma} \cdot d_{0} \cdot \eta_{c}}{2 \cdot \sigma_{II}}$

where d₀ is the droplet diameter before break-up, η_(c) is the viscosityof the continues phase, σ_(II) is the surface tension of the continuesphase and {dot over (γ)} is the shear.

The Weber number is a measure of the ratio between the forces acting todeform the droplet (shear, viscosity of the continuous phase) and theforces holding the droplet together (surface tension).

If a pair of PU and PO is not miscible, changing the processingconditions can contribute to making it happen. For example, increasingthe shear ({dot over (γ)}).

When referring to a viscosity ratio at processing conditions, in someembodiments it is meant that the ratio will have the specified value, orbe within the specified range, when the process is up and running atsteady state (i.e. start-up or shut down conditions are not relevant).In other embodiments it is useful to specify a specific shear rateand/or temperature, or to otherwise specific the processing conditionsmeant. In some embodiments the viscosity ratio is considered at atemperature above the melting point of the composition and a shear rateof 500 s⁻¹, a shear rate preferred if the alloy is to be injectionmoulded.

In some embodiments the viscosity ratio is considered at a temperatureabove the melting point of the composition and a shear rate of 1000 s⁻¹,or at a temperature above the melting point of the composition and ashear rate of 3000 s⁻¹. In any of these embodiments the temperature maybe at least 2 degrees C. above the melting point of the blend, at least5 degrees C. above the melting point of the blend, or even 2 or 5degrees C. above the melting point of the blend, and in still furtherembodiments the temperature may be from 150 to 200, or from 170 to 190,or of about 170, 180, or 190 degrees C. In any of these embodiments theviscosity ratio may be less than 1, less than 0.75, less than 0.5, oreven less than 0.4, while being at last 0.1.

To form an alloy of the invention, starting with a particular TPU, theviscosity of the PO can be modified to match the viscosity of the TPU byaltering the molecular weight of the PO. Increasing the molecular weightof the PO will increase the viscosity of the PO, and, likewise,decreasing the molecular weight of the PO will decrease the viscosity ofthe PO.

To form an alloy of the invention starting from a particular PO, theviscosity of the TPU can be modified by the molecular weight of the TPU(as stated above for PO). However, we have found that that TPU is moreshear dependent than the PO. Thus, by increasing shear rate in theprocessing conditions the viscosity of the TPU is decreased relativelymore than the viscosity of the PO.

We have also found that by increased processing temperature, theviscosity of the TPU decreases more than the viscosity of the PO. Thus,by increasing the processing temperature the viscosity of the TPU isdecreased relatively more than the viscosity of the PO. Accordingly, amatching viscosity at processing conditions can be found.

As presented in the foregoing, various variable has to be adjusted inorder to form the miscible blend, the alloy, of the invention. In oneaspect of the invention, those variables are adjusted by adding a thirdcomponent to the mixture: e.g. a plasticizer. It is presentlyanticipated that plasticizers have the effect that they lower thesurface tension and the viscosity of the TPU. The plasticizer has a dualrole; (1) it decreases the viscosity which helps to stabilize theinterface by decreasing the droplet diameter; (2) It helps to decreasethe interfacial tension.

In one aspect the plasticizers comprises hydrophobic butyl groups.

In a related aspect, the plasticizer is Citrofol.

One aspect of the invention relates to the pure mixture of a PO and aTPU as described. That is, the alloy consists essentially of TPU and PO.

In some embodiments, and more specifically embodiments where thecompositions of the invention are clear and/or have a reduced level ofhaze, the compositions of the invention include TPU and PO componentsthat have similar refractive indices. While not wishing to be bound bytheory, it is believed that similar refractive indices are necessary forthe resulting composition to be clear. The refractive index of amaterial can be measured with refractometers. They generally measuresome angle of refraction or the critical angle for total internalreflection for a liquid or solid material.

A convenient way to describe the similarity of the refractive index ofthe TPU component and the refractive index of the PO component includedin the compositions of the invention is to refer to the ratio of therefractive index of the TPU component to the refractive index of the POcomponent, as measured at room temperature. The closer the ratio is to1, the more similar the refractive indices are. In some embodiments theratio of the refractive index of the TPU component to the refractiveindex of the PO component is from 0.8 to 1.2, or from 0.9 to 1.1, orfrom 0.95 to 1.05, such as from 0.96 to 1.04 or from 0.97 to 1.03 orfrom 0.98 to 1.02, or even from 0.99 to 1.01 or even from 1.0 to 1.01.In some embodiments the ratio of the refractive index of the TPUcomponent to the refractive index of the PO component is less than 1.1,or less than 1.02 or even less than 1.01. In some of these embodimentsroom temperature may be considered to be about 20 degrees C.

Thus, one interesting option with the alloys of the invention is theformation of alloys wherein

-   -   the ratio between the refractive index of the TPU and the        refractive index of the PO is between 0.9 and 1.1 and in some        embodiments is between (0.99 and 1.01, or even 0.995 and 1.005);        and    -   the Haze value for both the TPU and the PO prior to compounding        is below 30.

Typically, the haze value is measured at 555 nm according to ASTMD1003-07 “Standard Test Method for Haze and Luminous Transmittance ofTransparent Plastics”.

One particular aspect of the invention relates to an alloy of athermoplastic polyurethane (TPU) and a Polyolefin (PO) having a ratio ofrefractive index between the TPU and the PO of between 0.9 and 1.1; andthe Haze value for both the TPU and the PO is below 30.

On series of embodiments relates to a composition comprising athermoplastic polyurethane (TPU) and a polyolefin (PO), wherein the TPUcomprises the reaction product of a polyisocyanate, (for example adiisocyanate), a chain extender, and an optional polyol, and wherein theTPU has at least one of the following properties:

(i) a chain extender to polyol molar ratio of at least 1.3;

(ii) a blend molecular weight (BMW) of at least 500; and

(iii) a hard segment content of less than 40%.

Suitable polyisocyanates to make the TPU include aromatic diisocyanatessuch as 4,4″-methylenebis-(phenyl isocyanate) (MDI), m-xylenediisocyanate (XDI), phenylene-1,4-diisocyanate,naphthalene-1,5-diisocyanate, and toluene diisocyanate (TDI); as well asaliphatic diisocyanates such as isophorone diisocyanate (IPDI),1,4-cyclohexyl diisocyanate (CHDI), decane-1,10-diisocyanate, anddicyclohexylmethane-4,4″-diisocyanate (H12MDI).

Mixtures of two or more polyisocyanates may be used. In some embodimentsthe polyisocyanate is MDI and/or H12MDI. In some embodiments thepolyisocyanate may include MDI. In some embodiments the polyisocyanatemay include H12MDI.

Suitable chain extenders to make the TPU include relatively smallpolyhydroxy compounds, for example lower aliphatic or short chainglycols having from 2 up to about 20 or in some cases from 2 up to about12 carbon atoms. Suitable examples include ethylene glycol, diethyleneglycol, propylene glycol, dipropylene glycol, 1,4-butanediol (BDO),1,6-hexanediol (HDO), 1,3-butanediol, 1,5-pentanediol, neopentylglycol,1,4-cyclohexanedimethanol (CHDM), 2,2-bis[4-(2-hydroxyethoxy)phenyl]propane (HEPP) and hydroxyethyl resorcinol (HER), and the like,as well as mixtures thereof. In some embodiments the chain extenders are1,4-butanediol and 1,6-hexanediol. Other glycols, such as aromaticglycols could be used, but in some embodiments the TPUs of the inventionare not made using such materials.

In some embodiments the chain extender used to prepare the TPU issubstantially free of, or even completely free of, 1,6-hexanediol. Insome embodiments the chain extender used to prepare the TPU includes acyclic chain extender. Suitable examples include CHDM, HEPP, HER, andcombinations thereof. In some embodiments the chain extender used toprepare the TPU includes an aromatic cyclic chain extender, for exampleHEPP, HER, or a combination thereof. In some embodiments the chainextender used to prepare the TPU includes an aliphatic cyclic chainextender, for example CHDM. In some embodiments the chain extender usedto prepare the TPU is substantially free of, or even completely free ofaromatic chain extenders, for example aromatic cyclic chain extenders.

Suitable polyols (hydroxyl terminated intermediates), when present,include one or more hydroxyl terminated polyesters, one or more hydroxylterminated polyethers, one or more hydroxyl terminated polycarbonates ormixtures thereof.

Suitable hydroxyl terminated polyester intermediates include linearpolyesters having a number average molecular weight (Mn) of from about500 to about 10,000, from about 700 to about 5,000, or from about 700 toabout 4,000, and generally have an acid number generally less than 0.5.The molecular weight is determined by assay of the terminal functionalgroups and is related to the number average molecular weight. Thepolyester intermediates may be produced by (1) an esterificationreaction of one or more glycols with one or more dicarboxylic acids oranhydrides or (2) by transesterification reaction, i.e., the reaction ofone or more glycols with esters of dicarboxylic acids. Mole ratiosgenerally in excess of more than one mole of glycol to acid arepreferred so as to obtain linear chains having a preponderance ofterminal hydroxyl groups. Suitable polyester intermediates also includevarious lactones such as polycaprolactone typically made fromε-caprolactone and a bifunctional initiator such as diethylene glycol.The dicarboxylic acids of the desired polyester can be aliphatic,cycloaliphatic, aromatic, or combinations thereof. Suitable dicarboxylicacids which may be used alone or in mixtures generally have a total offrom 4 to 15 carbon atoms and include: succinic, glutaric, adipic,pimelic, suberic, azelaic, sebacic, dodecanedioic, isophthalic,terephthalic, cyclohexane dicarboxylic, and the like. Anhydrides of theabove dicarboxylic acids such as phthalic anhydride, tetrahydrophthalicanhydride, or the like, can also be used. Adipic acid is a preferreddiacid. The glycols which are reacted to form a desirable polyesterintermediate can be aliphatic, aromatic, or combinations thereof,including any of the glycol described above in the chain extendersection, and have a total of from 2 to 20 or from 2 to 12 carbon atoms.Suitable examples include ethylene glycol, 1,2-propanediol,1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol,1,6-hexanediol, 2,2-dimethyl-1,3-propanediol, 1,4-cyclohexanedimethanol,decamethylene glycol, dodecamethylene glycol, and mixtures thereof.

Suitable hydroxyl terminated polyether intermediates include polyetherpolyols derived from a diol or polyol having a total of from 2 to 15carbon atoms, in some embodiments an alkyl diol or glycol which isreacted with an ether comprising an alkylene oxide having from 2 to 6carbon atoms, typically ethylene oxide or propylene oxide or mixturesthereof. For example, hydroxyl functional polyether can be produced byfirst reacting propylene glycol with propylene oxide followed bysubsequent reaction with ethylene oxide. Primary hydroxyl groupsresulting from ethylene oxide are more reactive than secondary hydroxylgroups and thus are preferred. Useful commercial polyether polyolsinclude poly(ethylene glycol) comprising ethylene oxide reacted withethylene glycol, poly(propylene glycol) comprising propylene oxidereacted with propylene glycol, poly(tetramethylene glycol) comprisingwater reacted with tetrahydrofuran (PTMEG). In some embodiments thepolyether intermediate includes PTMEG.

Suitable polyether polyols also include polyamide adducts of an alkyleneoxide and can include, for example, ethylenediamine adduct comprisingthe reaction product of ethylenediamine and propylene oxide,diethylenetriamine adduct comprising the reaction product ofdiethylenetriamine with propylene oxide, and similar polyamide typepolyether polyols. Copolyethers can also be utilized in the currentinvention. Typical copolyethers include the reaction product of THF andethylene oxide or THF and propylene oxide. These are available from BASFas Poly THF B, a block copolymer, and poly THF R, a random copolymer.The various polyether intermediates generally have a number averagemolecular weight (Mn) as determined by assay of the terminal functionalgroups which is an average molecular weight greater than about 700, suchas from about 700 to about 10,000, from about 1000 to about 5000, orfrom about 1000 to about 2500. A particular desirable polyetherintermediate is a blend of two or more different molecular weightpolyethers, such as a blend of 2000 M_(n) and 1000 M_(n) PTMEG.

Suitable hydroxyl terminated polycarbonates include those prepared byreacting a glycol with a carbonate. U.S. Pat. No. 4,131,731 is herebyincorporated by reference for its disclosure of hydroxyl terminatedpolycarbonates and their preparation. Such polycarbonates are linear andhave terminal hydroxyl groups with essential exclusion of other terminalgroups. The essential reactants are glycols and carbonates. Suitableglycols are selected from cycloaliphatic and aliphatic diols containing4 to 40, and or even 4 to 12 carbon atoms, and from polyoxyalkyleneglycols containing 2 to 20 alkoxy groups per molecule with each alkoxygroup containing 2 to 4 carbon atoms. Diols suitable for use in thepresent invention include aliphatic diols containing 4 to 12 carbonatoms such as butanediol-1,4, pentanediol-1,4, neopentyl glycol,1,6-hexanediol6, 2,2,4-trimethyl-1,6-hexanediol, 1,10-decanediol,hydrogenated dilinoleylglycol, hydrogenated dioleylglycol; andcycloaliphatic diols such as 1,3-cyclohexanediol,1,4-dimethylolcyclohexane, 1,4-cyclohexanediol,1,3-dimethylolcyclohexane, 1,4-endomethylene-2-hydroxy-5-hydroxymethylcyclohexane, and polyalkylene glycols. The diols used in the reactionmay be a single diol or a mixture of diols depending on the propertiesdesired in the finished product. Polycarbonate intermediates which arehydroxyl terminated are generally those known to the art and in theliterature. Suitable carbonates are selected from alkylene carbonatescomposed of a 5 to 7 member ring. Suitable carbonates for use hereininclude ethylene carbonate, trimethylene carbonate, tetramethylenecarbonate, 1,2-propylene carbonate, 1,2-butylene carbonate, 2,3-butylenecarbonate, 1,2-ethylene carbonate, 1,3-pentylene carbonate,1,4-pentylene carbonate, 2,3-pentylene carbonate, and 2,4-pentylenecarbonate. Also, suitable herein are dialkylcarbonates, cycloaliphaticcarbonates, and diarylcarbonates. The dialkylcarbonates can contain 2 to5 carbon atoms in each alkyl group and specific examples thereof arediethylcarbonate and dipropylcarbonate. Cycloaliphatic carbonates,especially dicycloaliphatic carbonates, can contain 4 to 7 carbon atomsin each cyclic structure, and there can be one or two of suchstructures. When one group is cycloaliphatic, the other can be eitheralkyl or aryl. On the other hand, if one group is aryl, the other can bealkyl or cycloaliphatic. Examples of suitable diarylcarbonates, whichcan contain 6 to 20 carbon atoms in each aryl group, arediphenylcarbonate, ditolylcarbonate, and dinaphthylcarbonate.

In some embodiments the TPU is made by reacting the polyisocyanate shownabove with the chain extender, with or without any polyol being present.The reactants to make the rigid TPU may be reacted together in a “oneshot” polymerization process wherein all of the components, includingreactants are added together simultaneously or substantiallysimultaneously to a heated extruder and reacted to form the TPU polymer.The reaction temperature utilizing urethane catalyst are generally fromabout 175° C. to about 245° C., and in some embodiments from about 180°C. to about 220° C. In some embodiments the equivalent ratio of thediisocyanate to the total equivalents of the hydroxyl terminatedintermediate and the diol chain extender is generally from about 0.95 toabout 1.05, desirably from about 0.97 to about 1.03, or from about 0.98to about 1.01.

Any of the TPU described above may also include one or more additives.These additives may be present with the components that react to formthe rigid TPU, or these additives may be added to the rigid TPU after ithas been prepared. Suitable additives include pigments, UV stabilizers,UV absorbers, antioxidants, lubricity agents, heat stabilizers,hydrolysis stabilizers, cross-linking activators, flame retardants,layered silicates, fillers, colorants, reinforcing agents, adhesionmediators, impact strength modifiers, antimicrobials, and of course anycombination thereof.

In some embodiments the TPU includes a TPU made from (i) a diisocyanatesthat includes 4,4″-methylenebis(phenyl isocyanate) (MDI), m-xylenediisocyanate (XDI), dicyclohexylmethane-4,4″-diisocyanate (H12MDI), orsome combination thereof; (ii) a chain extender that includes ethyleneglycol, diethylene glycol, propylene glycol, dipropylene glycol,1,4-butanediol, 1,6-hexanediol, 1,3-butanediol, 1,5-pentanediol,neopentylglycol, or some combination thereof; and (iii) a polyetherpolyols that includes poly(ethylene glycol) comprising ethylene oxidereacted with ethylene glycol, poly(propylene glycol) comprisingpropylene oxide reacted with propylene glycol, poly(tetramethyleneglycol) comprising water reacted with tetrahydrofuran (PTMEG).

In some embodiments the TPU of the invention has a chain extender topolyol molar ratio, calculated by the dividing the moles of chainextender used in the preparation of the TPU by the moles of polyol usedin the preparation of the TPU, of at least 1.3, at least 1.4, or even atleast 1.5. In some embodiments the a chain extender to polyol molarratio is from 1.3 to 2, or from 1.4 to 2, or from 1.3 to 1.8, or from1.4 to 1.8, or even about 1.5, about 1.6, or about 1.7.

In some embodiments the blend molecular weight (BMW) of the componentsused to prepare the TPU, which may be determined by hydroxyl analysis,to be at least 500, or at least 600, or even at least 700, and less than950, or no more than 900, or even no more than 850. In some embodimentsthe BMW is from 700 to 900, or even from 800 to 900, or from 750 to 850,or from 850 to 950.

In one aspect of the invention, the alloy comprises 30-70 (w/w) % TPU,preferably 40-60 (w/w) % polyurethane.

In a related aspect, the alloy comprises 30-70 (w/w) % polyolefin,preferably 40-60 (w/w) % polyolefin.

One embodiment of the invention relates to a mixture of TPU A with a POcontaining acrylic acid such a Nucrel 3990, Nucrel 0903HC, Escor 5000,Escor 5100, and/or Lucalen A3110M.

One embodiment of the invention relates to a mixture of TPU E with a POcontaining acrylic acid such a Nucrel 3990, Nucrel 0903HC, Escor 5000,Escor 5100, and/or Lucalen A3110M.

In some embodiments the alloy compositions of the invention may becrosslinked. In these embodiments the TPU used in the alloys of thisinvention contains some unsaturation in its backbone that is capable ofreacting to form crosslinks to produce a thermoset network. Thisunsaturation may be introduced into the TPU by incorporating glycolsthat contain carbon-carbon double bonds into the polymer as part of thechain extender or the hydroxyl terminated intermediate may havecarbon-carbon double bonds. In some embodiments, both the chain extender(hard segment component) and the hydroxyl terminated intermediate (softsegment component) have double bonds. This allows crosslinking to occurin both the hard and soft segments of the TPU. These glycol chainextenders that contain carbon-carbon double bonds are typically in theform of allyl moieties, such as those present in trimethylolpropanemonoallyl ether. Such unsaturation may also be present in the POcomponent used in the alloys of in the invention, but in someembodiments the hydrocarbon backbones of the PO may be crosslinkableeven without any unsaturation present. In any case, when activated (i.e.with E-Beam irradiation), the carbon-carbon double bonds, or othergroups available for crosslinking, within the components may reacttogether to produce crosslinks between different polymer chains in thealloy thus producing a crosslinked thermoset. The crosslinking used incuring the alloy can be generated by exposure to electron beamirradiation, gamma rays, ultra-violet light (in the presence of a photoinitiator in relatively clear polymeric formulations), or by chemicalfree radical generators such as aliphatic and aromatic peroxides, azocompounds, photo initiators, etc.

In some embodiments the alloy compositions of the invention may be usedas a compatibilizer in a blend of one of more TPU materials and one ormore PO materials, including blends of TPU and PO other than thosespecified above as useful in making the alloys of the invention. Inother words, the alloys of the invention, which must be made withspecific TPU and PO materials in order to produce the useful alloysdescribed herein, can improve the compatibility of other blends of TPUand PO that would otherwise not mix well and not product a stable anduseful composition. In such embodiments the alloys of the presentinvention may be present in a composition from 0.1 to 10 percent byweight, while the rest of the composition includes one or more TPUmaterials and one or more PO materials, where at one of the TPUmaterials or PO materials is different from the TPU or PO materialpresent in the alloy being used as the compatibilizer. In someembodiments the alloy is made of a first TPU and a first PO, asdescribed above, and then is combined with a second TPU and a second POwhere (i) the second TPU is different from the first TPU, (ii) thesecond PO is different from the first PO, or (iii) the second TPU isdifferent from the first TPU and the second PO is different from thefirst PO. The weight ratio of the second TPU to the second PO is notoverly limited and in some embodiments may be from 1:99 to 991 or from10:90 to 90:10, or from 30:70 to 70:30 or from 40:60 to 60:40. Thecompatibilized blend may contain one or more additional additives,including any of the additives described above. While not wishing to bebound by theory, it is believed that the compatibilized blend of TPU andPO that uses the alloy of the invention as a compatibilizer, will havebetter physical properties compared to the blend of the same TPU and POwhere the alloy of the invention is not present, and that this is due tothe alloy acting to improve the compatibility of the TPU and PO in theblend due to the same forces that cause the TPU and PO of the alloys ofthe invention to be some compatible. In such embodiments the inventionincludes compatibilized blends of TPU and PO that uses the alloy of theinvention as a compatibilizer, the process of making such blends, aswell as the use of the alloy of the invention as a compatibilizer in TPUand PO blends, including the use of the alloy to improve the physicalproperties of such blends, including the tensile strength, ultimateelongation, clarity/haze, etc. of the blend.

In some embodiments the alloys of the invention include a plasticizer.As noted above, it is believed that a plasticizer may work, in certaininstances, to improve the compatibly of a given pairing of TPU and PO,by bringing one or more of the important properties described above ofone or both of the components into better alignment with one another.The type of plasticizer used can be any of the known plasticizers foruse in TPU. The most common plasticizer types used are phthalates withbutyl benzyl phthalate being the most preferred. Plasticizers used inthe present invention can include phthalate based plasticizers, such as,di-n-butylphthalate, di-2-ethylhexyl phthalate (DOP), di-n-octylphthalate, diisodecyl phthalate, diisooetyl phthalate, octyldecylphthalate, butylbenzyl phthalate, and di-2-ethyhexyl phosphateisophthalate; aliphatic ester-based plasticizers, such asdi-2-ethylhexyl adipate (DOA), di-n-decyl adipate, diisodecyl adipate,dibutyl sebacate, and di-2-ethylhexyl sebacate; pyrometallitate-basedplasticizers, such as trioctyl trimellitate and tridecyl trimellitate;phosphate-based plasticizers, such as tributyl phosphate,tri-2-ethylhexyl phosphate, 2-ethylhexyldiphenyl phosphate, andtrieresyl phosphate; epoxy-based plasticizers, such as epoxy-basedsoybean oil; and polyester-based polymer plasticizers. For applicationsthat are sensitive from the toxicological point of view, such aschildren's toys and food contact,di-isononyl-eyelohexane-1,2-dicarboxylate (Hexamoll® DINCH from BASF)may be used as the plasticizer. A single plasticizer may be used or acombination of two or more plasticizers may be used. The selection ofthe desired plasticizer or combination of plasticizers will depend onthe TPU and PO components being used in the alloy, the end useapplication in mind for the composition, and various other factors wellunderstood by those skilled in the art of formulating such materials.The amount of plasticizer used, if present, may be from 0.1 to 30.0percent by weight of the overall composition or even from 5.0 to 20.0percent by weight of the overall composition. In such embodiments theinvention includes alloys of TPU and PO where a plasticizer is used toresult in an improved blend (the plasticizer resulted in the componentsbeing better matched to one another as described above, resulting in animproved blend compared to the blend that would have resulted withoutthe plasticizer), the process of making such alloys with the help of aplasticizer, as well as the use of the plasticizer in the alloy toimprove the compatibility of the TPU and PO components, including theuse of the plasticizer to improve the physical properties of theresulting alloy, including the tensile strength, ultimate elongation,clarity/haze, etc. of the alloy.

In some embodiments the alloys of the invention are essentially free ofany plasticizer, or even completely free of any plasticizer, and stillobtain the improved compatibility described above.

The blends of the invention may be used in various applications,including medical devices. Medical devices benefiting from the presentinvention include a variety of implantable or insertable medicaldevices, which are implanted or inserted into a subject, for example,for procedural uses or as implants. Examples include catheters (e.g.,renal or vascular catheters such as balloon catheters), guide wires,balloons, filters (e.g., vena cava filters, distal protection filters,etc.), stents (including coronary artery stents, peripheral vascularstents such as cerebral stents, urethral stents, ureteral stents,biliary stents, tracheal stents, gastrointestinal stents and esophagealstents), stent grafts, vascular grafts, vascular access ports,embolization devices including cerebral aneurysm filler coils (includingGuglilmi detachable coils and metal coils), myocardial plugs, pacemakerleads, left ventricular assist hearts and pumps, total artificialhearts, heart valves, vascular valves, tissue bulking devices, tissueengineering scaffolds for cartilage, bone, skin and other in vivo tissueregeneration, sutures, suture anchors, anastomosis clips and rings,tissue staples and ligating clips at surgical sites, cannulae, metalwire ligatures, orthopedic prosthesis such as bone grafts, bone plates,joint prostheses, as well as various other medical devices that areadapted for implantation or insertion into the body.

The medical devices of the present invention include implantable andinsertable medical devices that are used for systemic treatment, as wellas those that are used for localized treatment, including treatment ofany mammalian tissue or organ. Non-limiting examples are tumors; organsincluding the heart, coronary and peripheral vascular system (referredto overall as “the vasculature”), the urogenital system, includingkidneys, bladder, urethra, ureters, prostate, vagina, uterus andovaries, eyes, lungs, trachea, esophagus, intestines, stomach, brain,liver and pancreas, skeletal muscle, smooth muscle, breast, dermaltissue, cartilage, tooth and bone.

As used herein, “treatment” refers to the prevention of a disease orcondition, the reduction or elimination of symptoms associated with adisease or condition, or the substantial or complete elimination of adisease or condition. Preferred subjects (also referred to as“patients”) are vertebrate subjects, more preferably mammalian subjectsand more preferably human subjects. Specific examples of medical devicesfor use in conjunction with the present invention include vascularstents, such as coronary stents and cerebral stents, which may deliver atherapeutic agent into the vasculature for the treatment of restenosis.

In some embodiments, the medical devices of the invention includepolymeric regions that include one or more of the alloys of theinvention. In some embodiment the polymeric regions of the medicaldevices the invention correspond to an entire medical device. In otherembodiments, the polymeric regions correspond to one or more portions ofa medical device. For instance, the polymeric regions can be in the formof a component of a medical device, in the form of one or more fiberswhich are incorporated into a medical device, in the form of one or morepolymeric layers formed over all or only a portion of an underlyingmedical device substrate, and so forth. Layers can be provided over anunderlying substrate at a variety of locations, and in a variety ofshapes (e.g., in desired patterns, for instance, using appropriatemasking techniques, such as lithographic techniques). Materials for useas underlying medical device substrates include ceramic, metallic andpolymeric substrates. The substrate material can also be a carbon- orsilicon-based material, among others. As used herein a “layer” of agiven material is a region of that material whose thickness is smallcompared to both its length and width. As used herein a layer need notbe planar, for example, taking on the contours of an underlyingsubstrate. Layers can be discontinuous (e.g., patterned). Terms such as“film,” “layer” and “coating” may be used interchangeably herein. Asused herein, a “polymeric region” is a region that contains one or moreof the alloys described herein, and is typically 50 wt % to 75 wt % to90 wt % to 95 wt % alloy or more, to even 100 wt % alloy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1a and 1b are DSC measurements of a TPU A/Nucrel sample.

FIG. 2: Tensile strength and elongation as a function of PU/PO ratio.

FIGS. 3a-3d and 3f : TPU A/Nucrel—40/60. Cryo fractured surface, vaporstained with Ruthenium; backscatter mode; magnifications: a) 2500×, b)5000 k×, c) 10,000 k×, and d) 15,000 k×.

f) additional backscatter image at 10,000 k×.

FIGS. 4a-4d : TPU A/Nucrel—60/40. Cryo-fractured surface, vapor stainedwith Ruthenium; backscatter mode; magnifications at a) 2500×, b) 5000k×, c) 10,000 k×, and d) 15,000 k×.

EXAMPLES Example 1: TPU Formation

TPU A is prepared by reactive extrusion. An aromatic diisocyanate, a2000 molecular weight hydroxyl terminated polyether polyol, and a shortchain glycol chain extender, are reacted in an extruder. A conventionaladditive package is also added to the extruder. The components arecharged such that the chain extender to polyol molar ratio is about 1.5,the blend molecular weight is about 850, and the hard segment content ofthe resulting TPU is about 27.5%. TPU B is prepared by reactiveextrusion and uses the same aromatic diisocyanate, hydroxyl terminatedpolyether polyol, and a short chain glycol chain extender as TPU A,except that the polyol is a 1000 molecular weight polyol. A conventionaladditive package is also added to the extruder. The components arecharged such that the chain extender to polyol molar ratio is about 1.2,the blend molecular weight is about 495, and the hard segment content ofthe resulting TPU is about 40%.

TPU C is prepared by reactive extrusion and uses the same aromaticdiisocyanate, hydroxyl terminated polyether polyol, and a short chainglycol chain extender as TPU A. A conventional additive package is alsoadded to the extruder. The components are charged such that the chainextender to polyol molar ratio is about 1.2, the blend molecular weightis about 950, and the hard segment content of the resulting TPU is about25%.

TPU D is commercially available from BASF under the product nameElastollan® 1180A. TPU D is believed to be a polyether TPU made using1000Mn PolyTHF and having about 37% hard segment.

TPU E is commercially available from BASF under the product nameElastollan® 1160A. TPU E is believed to be a polyether TPU based on1400Mn PolyTHF having about 29% hard segment and about 15% plasticizer(acetyltributyl citrate).

TPU F is commercially available from BASF under the product nameElastollan® 1175A.

TPU G is commercially available from Bayer under the product nameDesmopan® 3360A.

TPU H is commercially available from Bayer under the product nameDesmopan® 9370A.

Example 2: PO Formation

Nucrel® 3990 is a copolymer of ethylene and acrylic acid with an acrylicacid content of 9 w/w % commercially available from DuPont also referredto as “Nucrel” below.

Escor™ 5000 and Escor™ 5100 are copolymers of ethylene and acrylic acidwith an acrylic acid content of 6 w/w % and 11 w/w % respectivecommercially available from by ExxonMobil.

Flexirene® MS 40 A is a linear medium density polyethylene (LMDPE)commercially available from by Polimeri Europa.

Nucrel 0903HC is an ethylene-methacrylic acid copolymer resin, made withnominally 9.0 wt % methacrylic acid and supplied by DuPont.

Luca A3110M medium/high density polyethelene copolymer with 4% acrylicacid and 8% butyl acrylate and is supplied by LyondellBasell.

Example 3: Alloy Formation

This experiment describes the preparation of a blended composition inaccordance with the present invention. Compositions were made containingeither a sole ingredient of one of the invention blend components or a60/40 w/w combination thereof.

The individual components were fed into a 16 mm co-rotating twin screwextruder with a 40:1 L/D ratio. The screw configuration contained aplasticizing zone and 3 mixing zones made from kneading elements. Duringcompounding the screws ran with a speed of 200 rpm and with thefollowing temperature profile:

° C. Die Zone 8 Zone 7 Zone 6 Zone 5 Zone 4 Zone 3 Zone 2 Zone 1 FeedSetting 170 170 180 180 180 180 185 185 0 0 Actual 170 170 180 180 179180 184 184 122 83

The polymer melts were extruded through a slit die of 1×45 mm and cooleddown on chill rollers (temperature 10° C.).

The thermoplastic polyurethanes were dried prior to compoundingaccordingly to the recommendations stated by the manufactures. A HELIOSdry-air dryer was used. The polyolefin and polyolefin copolymers werenot dried before compounding.

The experiments below describe the preparation of further blendedcompositions in accordance with the present invention.

BLEND 2 is a 25/75 w/w blend of TPU A and Nucrel 3990, a copolymer ofethylene and acrylic acid.

BLEND 3 is a 50/50 w/w blend of TPU A and Nucrel 3990, a copolymer ofethylene and acrylic acid.

BLEND 4 is a 75/25 w/w blend of TPU A and Nucrel 3990, a copolymer ofethylene and acrylic acid.

For BLEND 2, BLEND 3, and BLEND 4, for each run the individualcomponents are fed into a 30 mm diameter WP ZSK30 co-rotating twin screwextruder with a 29:1 L/D ratio. The screw configuration contains aplasticizing zone and 4 mixing zones made from kneading elements. Duringcompounding the screws are run to the same torque level, here 40%+/−3%,at rates of 12 and 20 pounds per hour (5.4 kg/hr and 9.0 kg/hr). Runsfor each blend are completed using the following temperature profiles,where samples are collected under each temperature profile once theprocess had stabilized.

Temperature Profile for BLEND 2 Zone 1 2 3 4 Die Setting 185° C. 185° C.179° C. 171° C. 171° C.

Temperature Profile for BLEND 3 (−15° C.) Zone 1 2 3 4 Die Setting 170°C. 170° C. 164° C. 156° C. 156° C.

Temperature Profile for BLEND 4 (+15° C.) Zone 1 2 3 4 Die Setting 200°C. 200° C. 194° C. 186° C. 186° C.

The polymer melts were extruded through a two-hole strand die onto acooling belt, and were dried for 24 hours at 82° C. Several samples arealso cooled by a chilled water bath. The thermoplastic polyurethaneswere dried prior to compounding according to the manufacturerrecommendations. The polyolefins and polyolefins copolymers were notdried before compounding.

The samples were visually compared regarding haze and opaqueness. Allsamples collected in BLEND 2, BLEND 3, and BLEND 4 showed low haze andopaqueness.

Example 4 Haze of Alloys

In order to evaluate the light-transmitting properties of the blends thehaze values were measured using a spectrophotometer and an integratingsphere according to ASTM D1003-07 “Standard Test Method for Haze andLuminous Transmittance of Transparent Plastics”. According to thestandard materials having a haze value greater than 30% are considereddiffusing.

Measurement Conditions

Haze was measured as described in ASTM D1003-07 where a shutter with areflection standard is moved between the two positions and the haze iscalculated as

${haze} = {( {\frac{T_{is}}{T_{t}} - \frac{T_{i}}{100}} ) \times 100\%}$

where T_(i), T_(is) and T_(t) are in percentage (note that with theinstrument normalization the incident light=100%).

Results

The haze was determined for different blends on samples with a thicknessof 0.80 mm. at 550 nm—about the center wavelength for visible light.

Composition by Haze at 550 Polyurethane Polyolefin weight nm TPU B —100/0  16.5 TPU B Nucrel 3990 60/40 85.6 TPU B Escor 5000 60/40 78.6 TPUB Escor 5100 60/40 77.2 TPU B Flexirene MS40A 60/40 81.2 TPU A — 100/0 18.2 TPU A Nucrel 3990 60/40 29.3 TPU A Nucrel 0903HC 60/40 20.2 TPU AEscor 5000 60/40 30.9 TPU A Escor 5100 60/40 31.3 TPU A Flexirene MS40A60/40 48.6 TPU A Lucalen A3110M 60/40 28.3 TPU C — 100/0  56.0 TPU CNucrel 3990 60/40 47.3 TPU C Escor 5000 60/40 46.8 TPU C Escor 510060/40 47.2 TPU C Flexirene MS40A 60/40 69.3 TPU D — 100/0  7.1 TPU DEscor 5100 60/40 75.3 TPU E — 100/0  23.1 TPU E Escor 5100 60/40 32.3TPU F — 100/0  26.3 TPU F Escor 5100 60/40 84.4 — Nucrel 3990  0/10013.7 — Escor 5000  0/100 9.0 — Escor 5100  0/100 15.1 — Flexirene MS40A 0/100 63.8

TPU B is a transparent and clear material but when it is compounded withpolyolefins the blends become white or opaque with a high haze value.

TPU A is also a transparent polyurethane but when it is compounded withpolyolefins containing acrylic acid the resulting blends aresurprisingly a lot more clear and transparent in comparison with theidentical blends with TPU B.

When compounded with Flexirene MS40A, LMDPE the blend is opaque. Thepure Flexirene is a white crystalline material so to obtain atransparent blend the pristine materials need at least to be clear fromthe beginning.

TPU C is an opaque polyurethane but when compounded with polyolefinscontaining acrylic acid the resulting blends are less opaque than thepristine TPU C and less hazy that the identical blends of TPU B. Eventhe blend containing Flexirene has a lower haze value than the same bendof TPU B.

From the haze measurements it can be seen that TPU A and TPU C resultsin blends with lower haze values than TPU B when compounded withpolyolefins. Especially TPU A blended with polyolefins containingacrylic acid gives transparent materials.

Example 5 Elongation of Alloys

We tested the alloys of TPU A with varying content of Nucrel 3990(referred to as “Nucrel” below) at the following TPU/Nucrel ratios;25/75, 40/60, 50/50, 60/40, and 75/25. These formulations were testedfor hardness (ASTM D2240), thermal properties (modulated DSC, ASTMD3418) and mechanical properties (ASTM D412).

As shown in FIG. 2 the mechanical properties remain within a very narrowrange independent of the alloy composition. That allows for alloys withhigh TPU content to obtain improved olefin compatibility, and highabrasion resistance and alloys with low TPU content to obtain blendswith significantly reduced materials costs (as TPU is a significantlymore expensive material compared to a PO) and hydrophobic low densitywhile maintaining acceptable physical properties. This is an interestingan unexpected observation. While not wishing to be bound by theory, webelieve these mechanical data along with transparency results suggestthat a quite stable interface is being formed independent of thecomposition of TPU A/Nucrel alloy such that the two phases do notmacro-phase separate in contrast to what one would generally expectconsidering the thermodynamic incompatibility of these materials.Furthermore, this stable and potentially broad interface (or interphase)present in the compositions of the invention, and as demonstrated by thedata herein, is very effective in stress transfer when the alloy isstrained. As one might expect, the hardness values for the alloys are inbetween the hardness values of each component (i.e. virgin TPU A andvirgin Nucrel) but the other physical properties are no so adjusted. Inthis way, when considering the hardness and mechanical values, thesealloys behave like two compatible polymers.

Nucrel 3990 TPU A Con- ASTM D2240** ASTM D412** ASTM D412** Content*tent* Hardness (Sh. A) Tensile Str Elongation 0 100 97 24 550 25 75 9422 596 40 60 91 23 627 50 50 89 21 622 60 40 84 21 608 75 25 79 19 610100 0 75 27 765 *Content values are weight percent values. **ASTM testresults are each averages of five test results.

Example 6 DSC of Alloys

We ran a thermal analysis (modulated DSC, ASTM D3418) of the alloys ofour invention. In an illustrative example, we took the TPU A/Nucrel40/60 sample (FIG. 1). In the modulated DSC measurements a sinusoidalheat profile is applied on top of a conventional linear heat flow. Thisway the total heat flow is separated into two parts, namely reversingheat flow and non-reversing heat flow. The reversing heat flow is theheat capacity (or thermodynamic) component and non-reversing heat flowis the kinetic component of the total heat flow. Thus the thermodynamicor heat capacity dependent transitions such as glass transition areseparated from kinetic transitions such as enhthalpic relaxation.

FIG. 1 shows reversing first heat, second heat and cooling curves, thefirst heat curve consists of a plethora of interfaces as illustrated bythe two glass-transitions (Tg): one at 2.4° C., one at 43.7° C. Thesetwo are between the Tg of TPU A and the Nucrel 3990 (the Tg of virginTPU A is −64° C., virgin Nucrel has a very broad glass transitionstarting from −7° C. ending around 57.5° C.).

Interestingly, as shown in FIG. 1, in the second heat curve we only findone Tg in-between the two previous Tg's. While not wishing to be boundby theory, this suggests that there are essentially two phases in thecomposition; a TPU-rich phase and a Nucrel-rich phase. In the firstheating cycle the material is heated up to 250° C. where everything ismolten and very mobile and then it is cooled down to −90° C. and heatedback up again. During the second heating one Tg is observed suggestingone-phase (or interphase) or phase-mixed morphology. However, sincethese materials are not covalently bonded (this is proved by NMR andsolvent extraction studies) each phase tries to separate with time toform a morphology which is observed during the first heating cycle. Butsince no deterioration in the physical properties or transparency of thematerial with time was observed, we believe the sample micro-phase (notmacro-phase) separates. This is again is believed to be due to presenceof a stable interface.

Furthermore, the presence of two Tg and micro-phase separated morphologysuggests that the material acts like a segmented copolymer (i.e.copolyester, polyurethane, polyuria, copolyetheramide, etc. . . . )where two incompatible phases are covalently bonded even though thesample is only a melt blend.

Example 7 SEM of Alloys

The samples were cryo-fractured and stained before running with SEM.Both backscattered electron (FIG. 3 and FIG. 4) and secondary electronimages are obtained. SEM pictures of 40/60 (TPU A/Nucrel) show narrowdistribution of TPU droplets in the Nucrel phase (40/60). On the otherhand the SEM image of 60/40 (TPU A/Nucrel) shows development of aco-continuous morphology similar to microphase separated segmentedcopolymer.

Example 8 Viscosity of Alloys

The apparent viscosities of all the virgin materials and TPU A/Nucrelalloys were determined using capillary rheometer (Goettfert Rheotester2000, with capillary die of 1 mm and L/D ratio of 30) the samples wererun at three temperatures; 170, 180, and 190 C which cover thetemperature range used during compounding. The apparent viscosity valuesand ratios at 100 1/s, 1000 1/s, and 3000 1/s shear rates at eachtemperature are listed in the attached table.

Shear Rate (1/s) TPU A TPU B TPU C TPU D TPU E Nucrel App. Vis. (Poise)at 170 C.  100 40000 40000 27000 40000 13000 5700 1000 7500 9000 60009000 3800 1800 3000 3400 2700 1800 970 Nucrel/TPU 0.29 0.36 0.54 1.00TPU/Nucrel 3.51 0.00 2.78 0.00 1.86 1.00 App. Vis. (Poise) at 180 C. 100 21000 23000 15000 29000 9000 5000 1000 5800 6400 4700 8000 30001700 3000 2600 3000 2000 3000 1300 880 Nucrel/TPU 0.34 0.29 0.44 0.290.68 1.00 TPU/Nucrel 2.95 3.41 2.27 3.41 1.48 1.00 App. Vis. (Poise) at190 C.  100 12000 16000 9000 18000 5000 3800 1000 4000 4900 3400 55002300 1400 3000 2000 2200 1700 3700 1200 750 Nucrel/TPU 0.38 0.34 0.440.20 0.63 1.00 TPU/Nucrel 2.67 2.93 2.27 4.93 1.60 1.00

Example 9: Determination of Refractive Index

Refractive Index Nucrel 1.4930 TPU A 1.5039 TPU B 1.5326 TPU C 1.5048TPU D 1.5321 TPU E 1.5046

The samples were prepared and analyzed in accordance with ASTM D-542-95.A circular cross section, one from each pellet, was used. The sampleswere either egg-shaped or rod-like pellets. A single section,perpendicular to the longest length of the pellet, was excised with amicrotome blade and used as an individual measurement of refractiveindex. Thus each refractive index measurement represents a differentpellet. Readings were only obtained if the small pellet cross sectionwas nearly centered on the Refractometer prism. At least five specimens,one each per pellet, were tested. Average deviation with 5 specimens wassmall. Otherwise more pellets could have been used. Specimens were cutwith a microtome blade from each pellet. Measurements were taken at(25.0+/−0.1) degrees Celsius using an ATAGO Abbe Type 3T Refractometerheld at temperature using a constant temperature bath. Prior to sampleanalysis the instrument was checked for accuracy using a polished glassstandard at 25° C. (1.5162). Five measurements of the specimens weremade using sodium D rays (589.3 nm wavelength). With the glass standarda small amount of 1-bromonaphthalene (refractive index=1.64) was used onthe specimen to wet the interface between the sample and the prism ofthe instrument.

Both TPU B and TPU D have indices at 1.5321 and 1.5326, which are verydifferent from Nucrel 3990, which has a refractive index of 1.4930. Thiscan explain why they form opaque blends.

Example 10: Surface Tension of Components Relative to PhysicalProperties of Alloys

The surface tension (ST) of various components, along with eachcomponent's refractive index (RI) were collected and compared to thephysical properties of alloys made from various combinations of thecomponents, including the haze seen in each alloy at 550 nm. The surfacetension of the components was measured by an analysis described in thefollowing journal article: N. J. Alvarez, L. M. Walker, and S. L. Anna,A non-gradient based algorithm for the determination of surface tensionfrom a pendant drop: application to low Bond number drop shapes.,Journal of colloid and interface science, vol. 333, no. 2, pp. 557-62,2009, incorporated herein by reference. The refractive index of thecomponent was measured as described above in Example 9. The differenceor delta (Δ) in the surface tension and refractive index of thecomponents of each alloy are also calculated. In the table below PO A isNucrel 3990 and PO B is Escor 5100. The results are presented in thetable below:

Alloy Composition Ex. TPU Component PO Component TPU:PO No. TPU ID ST RIPO ID ST RI wt ratio Δ ST Δ RI Haze 10-1 TPU B 29.3 1.5326 PO A 21.81.4930 60:40 7.5 0.0396 85.6 10-2 TPU B 29.3 1.5326 PO B 18.1 1.498760:40 11.2 0.0339 77.2 10-3 TPU A 19.8 1.5039 PO A 21.8 1.4930 60:40 2.00.0109 29.3 10-4 TPU A 19.8 1.5039 PO B 18.1 1.4987 60:40 1.7 0.005231.3 10-5 TPU E 27.3 1.5049 PO B 18.1 1.4987 60:40 9.2 0.0062 32.3 10-6TPU D 29.5 1.5321 PO B 18.1 1.4987 60:40 11.4 0.0334 75.3 10-7 TPU G27.6 1.5102 PO B 18.1 1.4987 60:40 9.5 0.0115 51.2 10-8 TPU H — 1.5082PO B 18.1 1.4987 60:40 — 0.0095 26.5

As the data shows, alloys where the components have more comparablesurface tensions, and especially when they also have more comparablerefractive index results, as demonstrated by smaller delta values, theresulting alloy is less hazy. Example 10-3 and Example 10-1 clearly showthis, were smaller delta ST and delta RI values correspond to Example10-3's lower haze value.

Each of the documents referred to above is incorporated herein byreference. Except in the Examples, or where otherwise indicated, allnumerical quantities in this description specifying amounts, reactionconditions, molecular weights, number of carbon atoms, etc., are to beunderstood as modified by the word “about.” Unless otherwise indicated,all percent and formulation values are on a molar basis. Unlessotherwise indicated, all molecular weights are number average molecularweights. Unless otherwise indicated, each chemical or compositionreferred to herein should be interpreted as being a commercial gradematerial which may contain the isomers, by-products, derivatives, andother such materials which are normally understood to be present in thecommercial grade. However, the amount of each chemical component ispresented exclusive of any solvent or diluent, which may be customarilypresent in the commercial material, unless otherwise indicated. It is tobe understood that the upper and lower amount, range, and ratio limitsset forth herein may be independently combined. Similarly, the rangesand amounts for each element of the invention can be used together withranges or amounts for any of the other elements. As used herein, theexpression “consisting essentially of” permits the inclusion ofsubstances that do not materially affect the basic and novelcharacteristics of the composition under consideration. All of theembodiments of the invention described herein are contemplated from andmay be read from both an open-ended and inclusive view (i.e. using“comprising of” language) and a closed and exclusive view (i.e. using“consisting of” language). As used herein parentheses are useddesignate 1) that the something is optionally present such thatmonomer(s) means monomer or monomers or (meth)acrylate meansmethacrylate or acrylate, 2) to qualify or further define a previouslymentioned term, or 3) to list narrower embodiments.

1. A composition comprising (i) a thermoplastic polyurethane (TPU), (ii)a polyolefin (PO), and (iii) a compatibilizing amount of an alloy of athermoplastic polyurethane (TPU) and a Polyolefin (PO), the alloy havingat least one of the following properties: a ratio between surfacetension of the TPU and surface tension of the PO measured above a melttemperature of the alloy is between 0.5 to 1.5; the PO contains at leastone functional group that can form long range interactions with one ormore segments of the TPU; and a viscosity of a discrete phase over aviscosity of a matrix phase is below 2 under processing conditions.
 2. Acomposition according to claim 1, wherein the PO is selected from thegroup consisting of polyethylene (PE), polypropylene (PP), copolymer ofpolyethylene, and copolymer of polypropylene.
 3. A composition accordingto claim 1, wherein the PO is formed from copolymers of monoolefins anddiolefins with each other or with vinyl monomers.
 4. A compositionaccording to claim 1, wherein the PO is a polyethylene.
 5. A compositionaccording to claim 1, wherein the PO is a Polypropylene.
 6. Acomposition according to claim 1, wherein the ratio between the surfacetension of the TPU and the surface tension of the PO above the melttemperature of the alloy is between 0.8 and 1.2.
 7. A compositionaccording to claim 1, wherein Mn for a polyTHF segment of the TPU isgreater than 1000 g/mol.
 8. A composition according to claim 1, whereinthe least one functional group that can form a long range interactionwith one or more segments of the TPU is a group that can form a hydrogenbonding with the one or more segments of the TPU.
 9. A compositionaccording to claim 1, wherein the viscosity of the discrete phase overthe viscosity of the matrix phase is between 10 and 0.1.
 10. Acomposition according to claim 1, wherein the discrete phase is the POphase, and the matrix phase is the TPU phase.
 11. A compositionaccording to claim 1, wherein a ratio between a refractive index of theTPU and a refractive index of the PO at room temperature is between 0.8and 1.2.
 12. A composition according to claim 1, wherein the TPU has ahaze below 30 and the PO has a haze below
 30. 13. A compositionaccording to claim 1, wherein the alloy further comprises a plasticizer.14. A composition according to claim 1, wherein the alloy consistsessentially of TPU and PO.
 15. A composition according to claim 1,wherein the alloy comprises 30-70 (w/w) % TPU.
 16. A compositionaccording to claim 1, wherein the alloy comprises 30-70 (w/w) %polyolefin.